Dishwasher appliances generally include a tub that defines a wash compartment. Rack assemblies can be mounted within the wash chamber of the tub for receipt of articles for washing. Spray assemblies within the wash chamber can apply or direct wash fluid towards articles disposed within the rack assemblies in order to clean such articles. Multiple spray assemblies can be provided including e.g., a lower spray arm assembly mounted to the tub at a bottom of the wash chamber, a mid-level spray arm assembly mounted to one of the rack assemblies, and/or an upper spray assembly mounted to the tub at a top of the wash chamber. Other configurations may be used as well.
Dishwasher appliances further typically include a fluid circulation system which is in fluid communication with the spray assemblies for circulating fluid to the spray assemblies. The fluid circulation system generally receives fluid from the wash chamber, filters soil from the fluid, and flows the filtered fluid either to the spray assemblies or to a drain. To facilitate the flow of filtered fluid to the spray assemblies and/or drain, a pump is typically included in the fluid circulation system.
One issue with presently known pumps for both dishwasher appliance applications and other applications is torque ripple during operation of the motor driving the impeller of the pump. Torque ripple can transmit undesirable movement to the surrounding housing and other structure. Additionally, torque ripple can increase the noise generated by the motor and pump during operation of the dishwasher appliance.
One conventionally known solution for reducing the negative effects of torque ripple in pumps has involved “isolation”, or vibration damping, of the entire motor from other components of the pump. This can undesirably result in inaccurate positioning of the shaft. Another conventionally known solution for reducing the negative effects of torque ripple in pumps has involved isolation of the entire pump (including the motor assembly), which can undesirably require increase in the size and decreases in the efficiency of the pump.
Accordingly, improved pumps, for various applications including uses in dishwasher appliances, are desired in the art. In particular, pumps having reduced negative effects of torque ripple which can additionally provide relatively accurate shaft placement, reduced size, and improved efficiency would be advantageous.